title: Safe magnetic resonance imaging scanning of patients with cardiac rhythm devices: a role for computer modeling.
abstract: BACKGROUND
  Although there are several hazards for patients with implanted pacemakers and defibrillators in the magnetic resonance imaging (MRI) environment, evaluation of lead electrode heating is the most complex because of the many influencing variables: patient size, anatomy, body composition, patient position in the bore, scan sequence (radiofrequency power level), lead routing, and lead design. Although clinical studies are an important step in demonstrating efficacy, demonstrating safety through clinical trials alone is not practical because of this complexity.
  
  
  OBJECTIVE
  The purpose of this study was to develop a comprehensive modeling framework to predict the probability of pacing capture threshold (PCT) change due to lead electrode heating in the MRI environment and thus provide a robust safety evaluation.
  
  
  METHODS
  The lead heating risk was assessed via PCT change because this parameter is the most clinically relevant measure of lead heating. The probability for PCT change was obtained by combining the prediction for power at the electrode-tissue interface obtained via simulations with a prediction for PCT change as a function of radiofrequency power obtained via an in vivo canine study.
  
  
  RESULTS
  The human modeling framework predicted that the probability of a 0.5-V PCT change due to an MRI scan for the Medtronic CapSureFix MRI SureScan model 5086 MRI leads is <1/70,000 for chest scans and <1/10,000,000 for either head scans or lower torso scans.
  
  
  CONCLUSIONS
  The framework efficiently models millions of combinations, delivering a robust evaluation of the lead electrode heating hazard. This modeling approach provides a comprehensive safety evaluation that is impossible to achieve using phantom testing, animal studies, or clinical trials alone.
authors.affiliation: Cleveland Clinic, Cleveland, Ohio. Electronic address: wilkofb@ccf.org.
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Wilkoff
authors.forename: Timothy
authors.initials: T
authors.lastname: Albert
authors.forename: Mariya
authors.initials: M
authors.lastname: Lazebnik
authors.forename: Sung-Min
authors.initials: SM
authors.lastname: Park
authors.forename: Jonathan
authors.initials: J
authors.lastname: Edmonson
authors.forename: Ben
authors.initials: B
authors.lastname: Herberg
authors.forename: John
authors.initials: J
authors.lastname: Golnitz
authors.forename: Sandy
authors.initials: S
authors.lastname: Wixon
authors.forename: Joel
authors.initials: J
authors.lastname: Peltier
authors.forename: Hyun
authors.initials: H
authors.lastname: Yoon
authors.forename: Sarah
authors.initials: S
authors.lastname: Willey
authors.forename: Yair
authors.initials: Y
authors.lastname: Safriel
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000628:therapy*; D003198:Computer Simulation; D004195:Disease Models, Animal; D004285:Dogs; D004867:Equipment Design; D004869:Equipment Safety; D006801:Humans; D021621:Imaging, Three-Dimensional; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D010138:Pacemaker, Artificial; D019047:Phantoms, Imaging; D015203:Reproducibility of Results
keywords: 5086 MRI lead; AAMI; Association for the Advancement of Medical Instrumentation; Computer modeling; Hazards; ISO; International Organization for Standardization; Lead electrode heating; MR conditional; MRI; Magnetic resonance imaging; PCT; RF; SureScan; magnetic resonance imaging; pacing capture threshold; radiofrequency